oatpp/changelog/1.1.0.md

# Oat++ 1.1.0

Oat++ `1.1.0` is introducing breaking changes. 
Please read carefully to prepare for migration.

Feel free to ask questions - [Chat on Gitter](https://gitter.im/oatpp-framework/Lobby)

Contents:
- [No More ObjectWrapper](#no-more-objectwrapper)
- [Object-Mapping Simplified Primitives](#object-mapping-simplified-primitives)
- [Object-Mapping std Collections](#object-mapping-std-collections)
- [Type oatpp::Any](#type-oatppany)
- [Type oatpp::Enum](#object-mapping-enum)
- [DTO - Hashcode & Equals](#dto-hashcode-and-equals)
- [DTO - Fields Annotation](#dto-fields-annotation)

## No More ObjectWrapper

`ObjectWrapper` is a base-class for oatpp core types (`oatpp/core/Types.hpp`).
The explicit `::ObjectWrapper` qualifier is removed.

### DTO:

```cpp
class MyDto : oatpp::DTO { // <--- Notice the 'oatpp::DTO' now. NOT the 'oatpp::Object'

  DTO_INIT(MyDto, DTO)
  
  DTO_FIELD(Object<MyDto>, nested);             // <--- Notice the oatpp::Object<T> for Objects, instead of T::ObjectWrapper
  DTO_FIELD(List<Any>, listOfAny);              // <--- No '::ObjectWrapper' for collections.
  DTO_FIELD(Fields<List<String>>, mapOfLists);

}
```

### ApiController:

```cpp
ENDPOINT("POST", "body-dto", postWithBody,
         BODY_DTO(Object<MyDto>, body)) {
  ...    
}
```

### ApiClient:

```cpp
API_CALL("POST", "body-dto", postWithBody, BODY_DTO(Object<MyDto>, body))
```

### In Other Code-Blocks

```cpp
oatpp::Object<MyDto> myDto;
oatpp::List<oatpp::Object<MyDto>> listOfDtos;

...

auto myDto = objectMapper->readFromString<Object<MyDto>>(json);
auto listOfDtos = objectMapper->readFromString<List<Object<MyDto>>>(json);
```

## Object-Mapping Simplified Primitives

No more `<primitive>->getValue()`.

```cpp
oatpp::Int32 objV = 32;
v_int32 v = objV; // You may check for nullptr before doing this

bool equals = v == objV; // <--- NO NEED to check for nullptr here
bool isNull = objV == nullptr;
bool isNull = !objV;
```

## Object-Mapping std Collections

Now `oatpp::<mapping-enabled-collections>` are based on `std::<collections>`

Example:

```cpp
oatpp::Vector<oatpp::String> vector({});
oatpp::List<oatpp::String> list({});
oatpp::UnorderedSet<oatpp::String> set({});
oatpp::Fields<oatpp::String> pairList({});
oatpp::UnorderedFields<oatpp::String> hashMap({});

oatpp::Vector<oatpp::String> vector = {"a", "b", "c"};
oatpp::List<oatpp::String> list = {"a", "b", "c"};
oatpp::UnorderedSet<oatpp::String> set = {"a", "b", "c"};
oatpp::Fields<oatpp::String> pairList = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"}};
oatpp::UnorderedFields<oatpp::String> hashMap = {{"k1", "v1"}, {"k2", "v2"}, {"k3", "v3"}};

vector[0] = "z"; // <--- Complexity = O(1);
vector->push_back("www");

list[0] = "z"; // <--- Complexity = O(n);
list->push_back("www");

bool contains = set["b"]; // <--- Complexity = O(1);
set->insert("z")

auto value = pairList.getValueByKey("k1"); // <--- Complexity = O(n); // note '.' here, not '->' !!!
pairList->push_back({"key_z", "z"}); 

hashMap["k1"] = "z" // <--- Complexity = O(1);
hashMap->insert({"key_z", "z"});

for(auto& item : *vector) {
  ...
}

for(auto& item : *list) {
  ...
}

for(auto& item : *set) {
  ...
}

for(auto& pair : *pairList) {
  ...
}

for(auto& pair : *hashMap) {
  ...
}
```

## Type oatpp::Any

The new Type Introduced - `oatpp::Any`.

Now it's possible to do like this:

```cpp
class MyDto : public oatpp::DTO {

  DTO_INIT(MyDto, DTO)
 
  DTO_FIELD(Any, any); // Put any oatpp::<Type> here
  DTO_FIELD(List<Any>, listOfAny)
  DTO_FIELD(Fields<Any>, mapOfAny);

};
```

### JSON Serializer

Will serialize Any depending on the value type it stores.

### JSON Deserializer

Will try to guess the type of the `Any`. 
Currently, `Any` is deserialized as follows:

- JSON objects are deserialized to `Any` holding `oatpp::Fields<Any>`.
- JSON lists are deserialized to `Any` holding `oatpp::List<Any>`.
- JSON `null` is deserialized to `Any` holding `nullptr`.
- JSON `true`/`false` is deserialized to `Any` holding `oatpp::Boolean`.
- JSON `number` is deserialized to `Any` holding `oatpp::Float64`.

### Example

```cpp
oatpp::Fields<oatpp::Any> map = {
  {"title", oatpp::String("Hello Any!")},
  {"listOfAny",
   oatpp::List<oatpp::Any>({
     oatpp::Int32(32),
     oatpp::Float32(0.32),
     oatpp::Boolean(true)
   })
  }
};

auto json = mapper->writeToString(map); 
```

**Output:**

```json
{
  "title": "Hello Any!",
  "listOfAny": [
    32,
    0.3199999928474426,
    true
  ]
}
```

## Object-Mapping Enum

Enum is added to DTO codegen.

### Declaration 

```cpp
#include OATPP_CODEGEN_BEGIN(DTO)

ENUM(Enum1, v_int32,            // <-- type is mandatory 
     VALUE(V_1, 1),             // <-- integral value is mandatory
     VALUE(V_2, 2, "name-2"),
     VALUE(V_3, 3, "name-3", "description_3")
)

#include OATPP_CODEGEN_END(DTO)
```

This will generate:

```cpp
enum class Enum1 : v_int32 {
  V_1 = 1,
  V_2 = 2,
  V_3 = 3
}

... // PLUS Meta here
```

Current limitation - `ENUM` can not be declared nested in the class :(.
This may be fixed later.

### Usage

#### DTO

```cpp
ENUM(MyEnum, v_int32,
  VALUE(V1, 10, "enum1-v1"),
  VALUE(V2, 20, "enum1-v2"),
  VALUE(V3, 30, "enum1-v3")
);

class MyDto : public oatpp::DTO {

  DTO_INIT(MyDto, DTO)

  DTO_FIELD(Enum<MyEnum>, enum1);            // Default interpretation - AsString
  DTO_FIELD(Enum<MyEnum>::NotNull, enum2);   // NOT_NULL constraint for Ser/De

  DTO_FIELD(Enum<MyEnum>::AsString, enum3);  // Ser/De as string name
  DTO_FIELD(Enum<MyEnum>::AsNumber, enum4);  // Ser/De as a corresponding integral value

  DTO_FIELD(Enum<MyEnum>::AsString::NotNull, enum5);
  DTO_FIELD(Enum<MyEnum>::AsNumber::NotNull, enum6);

};
```

#### ApiController

```cpp
  ENDPOINT("GET", "enum/as-string", testEnumString,
           HEADER(Enum<AllowedHeaderValues>::AsString, enumValue, "X-MyEnum"))
  {
    return createResponse(Status::CODE_200, "OK");
  }

  ENDPOINT("GET", "enum/as-number", testEnumNumber,
           HEADER(Enum<AllowedHeaderValues>::AsNumber, enumValue, "X-MyEnum"))
  {
    return createResponse(Status::CODE_200, "OK");
  }
```

#### ApiClient

```cpp
  API_CALL("GET", "enum/as-string", getWithEnumHeaderAsString, HEADER(Enum<AllowedHeaderValues>::AsString, enumValue, "X-MyEnum"))
  API_CALL("GET", "enum/as-number", getWithEnumHeaderAsNumber, HEADER(Enum<AllowedHeaderValues>::AsNumber, enumValue, "X-MyEnum"))
```

### Meta functions

```cpp
{
  auto entry = oatpp::Enum<MyEnum>::getEntryByName("<name>");
  auto entry = oatpp::Enum<MyEnum>::getEntryByValue(MyEnum::VALUE);
  auto entry = oatpp::Enum<MyEnum>::getEntryByUnderlyingValue(123);
  auto entry = oatpp::Enum<MyEnum>::getEntryByIndex(0);
  ...
  OATPP_LOGD("Entry", "%d, %s, %d, %d, %s", entry.index, entry.name, entry.value, entry.description);
}

{
 const auto& entries = oatpp::Enum<MyEnum>::getEntries();
 for(const auto& e : entries) {
  ...
 }
}
```

## DTO Hashcode and Equals

Now DTOs can be used as a Key in `unordered_map` and `unordered_set`.
The convenience `DTO_HC_EQ` (DTO_HASHCODE_AND_EQUALS) macro has been added.

```cpp
class User : public oatpp::DTO {

  DTO_INIT(User, DTO)

  DTO_FIELD(String, firstName);
  DTO_FIELD(String, lastName);

  DTO_HC_EQ(firstName, lastName) // List key fields that count in std::hash and "==","!=" operators. 

};
```

The `DTO_HC_EQ` macro works taking into account the `DTO_HC_EQ` declared in the parent DTO class.  

If no `DTO_HC_EQ` is declared in none of the DTO's parent classes the default behavior is:
- `std::hash` - is `v_uint64` representation of object address.
- operators `==` and `!=` - is comparison of object addresses.

## DTO Fields Annotation

Now it's possible to add a description for DTO fields, which will be automatically
displayed in swagger-UI.

```cpp
class MyDto : public oatpp::DTO {

  DTO_INIT(MyDto, DTO)

  DTO_FIELD_INFO(id) {
    info->description = "identifier";
  }
  DTO_FIELD(String, id);

};
```

*Note: The `description` is currently the only info you can add to the DTO field 
(This may be extended later). In order to provide the list of possible values - use the 
new Enum feature - [Type oatpp::Enum](#object-mapping-enum).*